Details:
Summary:
The mechanism of ink penetration and setting on paper determines the production rate and influences the final print quality. To develop inks and papers for inkjet and flexographic printing, it is important to quantify the degree of ink penetration and ink-dot spreading; the resolution of print is determined by spreading. The final position of ink pigments determines the ink density and the resolution of the printed product. The ink penetration rates in the thickness direction into nonwoven fabrics were characterized with a Bristow absorption wheel. The radial spreading behavior of micro ink drop onto nonwoven fabrics was measured by capturing images using a microscopic video camera. The spreading rates of the ink-dot radius on the sheets were determined. One- and three-dimensional models based on Darcy's law were applied to predict the ink radial spreading and the penetration into the nonwoven fabrics. The model links the void fraction, pore size, contact angle and the permeability coefficients of the substrates to the ink spreading radius and penetration depth. The results showed a high correlation between the experimental data and the predicted results in the both radial and thickness directions; however in a few cases, the absorption rates were different than expected. The results demonstrate that a combination of the contact angle and the permeability control spreading and penetration of ink. The three-dimensional model could predict liquid spreading and penetration rates into porous media such as synthetic nonwoven sheets.